1. Field of the Invention
The present invention relates generally to an in-tank dispenser and more particularly to a dispenser in which a solid product or products contained within the dispenser are dissolved in a reservoir containing water, thereby forming a solution and a measured amount of the solution is released as water in the toilet tank recedes when the flush valve is operated.
2. Description of the Prior Art
Prior art means for treating toilet tank water include a solid cake of product being placed at the bottom of the toilet tank. The solid cake would slowly dissolve and migrate into the tank water by diffusion. Another prior art device provides an enclosure and a reservoir for slowly dissolving a solid cake. The enclosure has openings that discharge the solution when the toilet is flushed and refilled when the water tank is refilled. This dispenser is generally located at the bottom of the tank and weighted down by a container weight or by placing gravel within the container. A major disadvantage of this type of dispenser is that there is migration or diffusion of the product into the tank water during long quiescent periods thereby resulting in over-dispensing.
Another prior art dispenser provides for dispensing a liquid concentrate into the tank water. A flow actuated mechanism releases the liquid concentrate from a liquid reservoir when the water level in the toilet tank drops and reseals the reservoir when the water level forces the float against a seal. While this dispenser works well for solutions of low surface tension, it is inoperative when surface tension is near that of water, or approximately 73 dynes per centimeter. Accordingly, this dispenser will not dispense liquid chlorine such as sodium hypochlorite unless a surface tension reducing agent is added. Sodium hypochlorite is a strong oxidizing agent and organic surfactants or other organic treatment materials have limited compatibility with a resulting loss in available chlorine or surfactant activity.
More recently, a passive dosing dispenser has been used in toilet tanks. The passive dosing dispenser includes a trapped air bubble to provide an air lock to isolate the product in the dispenser from the water in the tank.